Natural substances, botanical extracts, and complementary alternative medicines (CAMs) have been used in a variety of pathological conditions with success. Approximately $34 billion is spent on CAMs annually in the United States (MacLennan, Wilson, & Taylor, 2002). Polyphenols are antioxidant molecules contained within many foods. Common natural polyphenol sources are fruits, vegetables, nuts, chocolate, wine, and tea. Polyphenols have been recognized to exhibit anti-inflammatory, antimicrobial, and antineoplastic properties. Tea is currently the second most consumed beverage worldwide. Green tea, Camellia sinesis, is a popular drink that is consumed by millions of people and a source of polyphenols (Du et al., 2012). Green tea extracts (GTEs) are among the most widely used ancient herbal medicinal agents used (Liao, 2001). Catechins (polyphenols) are main active ingredients of scientific focus regarding green tea. Epigallocatechin gallate (EGCG) is a flavonoid with scavenging action that inhibits reactive oxygen species production. Because of the anti-inflammatory, antineoplastic, and antimicrobial properties that flavonoids exhibit, they have been used and examined in various conditions in dermatology. However, topical green tea has been investigated in the treatment of acne vulgaris as well. Sinecatechins, from Camellia sinesis, are currently approved for the topical treatment of external genital and perianal warts. However, topical green tea has been investigated in the treatment of acne vulgaris as well.

MECHANISM OF ACTION

Green tea flavonoids have shown a number of mechanisms. Green tea flavonoids have indirect antioxidant activity and inhibit enzymes that lead to increased oxidative stress (lipoxygenase). Camellia sinesis flavonoids have been shown to result in immune stimulation via activating and inducing macrophages, Langerhans cells, lymphocytes, interleukin-1[beta], tumor necrosis factor-[alpha], and interferon-[gamma]. In addition, there is inhibition of topoisomerase and promotion of apoptosis.

Acne vulgaris may be caused by multiple mechanisms including altered keratinization within pilosebaceous unit, increased production of sebum, proliferation of Propionibacterium acnes (P. acnes), and inflammation around pilosebaceous follicles. In addition, EGCG has been shown to exhibit an inhibitory effect on 5[alpha]-reductase, the enzyme responsible for the conversion of testosterone into dihydrotestosterone (Liao, 2001). The inhibition of 5[alpha]-reductase in the sebaceous glands with EGCG resulted in reduced production of sebum (Mahmood, Akhtar, Khan, Khan, & Saeed, 2010). In sebocytes, studies have shown that EGCG has antimicrobial effects against P. acnes, the bacteria responsible for most acne (Kallis, Price, Dosal, Nichols, & Keri, 2018).

In relation to acne vulgaris, EGCG inhibits nuclear factor kappa-light-chain-enhancer of activated B cells (NF-[kappa]B), which has been implemented in inflammatory lesions. Recent studies suggest that EGCG may suppress sebum production (Saric, Notay, & Sivamani, 2016) in the skin via suppression of sterol regulatory element-binding proteins and induce apoptosis of sebocytes (Yoon, Kwon, Min, Thiboutot, & Suh, 2013).

USES IN PRACTICE AND DOSING

Topical Green Tea/EGCG

In a trial of 20 subjects aged 15-36 years with mild-to-moderate acne, there was a statistically significant reduction in total lesion count by 58% and a 39% reduction in the mean severity index after 6 weeks of therapy with a twice-daily application of a 2% green tea lotion (Elsaie, Abdelhamid, Elsaaiee, & Emam, 2009).

In an 8-week, randomized, double-blinded, split-face clinical trial utilizing 1% or 5% EGCG solution twice daily versus 3% ethanol vehicle on the other side of the face, it was found that 1% and 5% EGCG solutions had similar efficacy. There was a statistically significant reduction in both inflammatory and noninflammatory lesions. In the 1% treatment group, there was a 79% reduction in noninflammatory lesions and 89% reduction in inflammatory lesions compared with baseline (Yoon et al., 2013).

Oral GTE

In a randomized, double-blinded, placebo-controlled trial of 80 individuals in Taiwan, 1500 mg of decaffeinated GTE taken by mouth daily for 4 weeks was compared with placebo (cellulose). Differences were noted in inflammatory lesion counts on the chin and nose and in the perioral region between the two groups (Lu & Hsu, 2016).

Adverse Reactions

Subtle adverse effects such as erythema and irritation have been observed. The likelihood of reactions appears to be dependent on the concentration used. No side effects were observed in patients receiving 1% EGCG (Yoon et al., 2013). In the 2% green tea lotion, stinging and itching were noted in two of 20 patients (Elsaie et al., 2009). Erythema and irritation were in four of 18 patients receiving the 5% EGCG solution; however, within a few hours, the reactions subsided (Yoon et al., 2013).

CONCLUSION

Botanical extracts and plant products have gained a large following in recent years. Catechins (polyphenols), specifically EGCG, are the main active ingredients within green tea. Many over-the-counter lotions are being marketed as containing green tea. Clinical results suggest that EGCG is effective in both inflammatory and noninflammatory acne lesions when used topically. Skin irritation is the most common adverse effect of topical EGCG and appears to be more likely to develop as the concentration increases. Results are limited to small studies, and larger controlled studies will be needed. Many patients may be seeking and utilizing various over-the-counter and natural products in their daily skin care routines that can benefit or possibly irritate the skin. As a practitioner, it is important to be aware of some natural product ingredients that may overlap with current pharmacologic agents. With EGCG, it is unclear how EGCG compares with conventional pharmacologic agents currently used in the treatment of acne. As many pharmacologic agents have a natural origin and marketing continues to increase with social media, practitioners may find patients are utilizing CAM products when questioned directly.

REFERENCES